Where does “Berlusconi” come from?

I can't write this etymology summary because the chain provided contains only Italian "Berlusconi" with no older language sources, making it impossible to trace the word's origin or establish the multi-language chain required by the rules. To write an accurate etymology, I would need the chain extended back through earlier languages (for example, if this derives from a surname, its Italian origin, and potentially Latin or other sources). Could you provide the complete etymological chain?

Ancestry of “Berlusconi”, step by step

Step	Language	Word	Meaning
1	Italian	Berlusconi	—
2	Italian	berlusco	doubly shady or sinister
3	Italian	losco	sullen, surly; shady, suspicious
4	Latin	Luscus	a cognomen used by the
5	Latin	luscus	one-eyed; with one eye shut; half blind
6	Proto-Indo-European	lewk-	bright; to shine; to see

Words derived from “Berlusconi”

Berlusconian
Berlusconism

Every word from Proto-Indo-European lewk- →Every word from Latin luscus →Every word from Latin Luscus →